This invention relates to fuel nozzle and support assemblies for turbine type power plants and particularly to fuel nozzle and support assemblies having water injection means with smoke reduction characteristics.
One of the criteria necessary for an aircraft engine to meet its specification is the quantity of the smoke emitted in the exhaust. In the interest of cost reduction the two piece nut assembly for the fuel nozzle nut of the JT-9D engine manufactured by Pratt & Whitney Aircraft Group, Division of United Technologies Corporation was made in a single piece. During the development stages a characteristic of that particular assembly was the fact that the single piece nut caused exceedingly high smoke emission when the engine was operated in the water injection mode. This was unsatisfactory from the engine specification requirements. The cause of the problem was not easily defined and while the solution was perhaps simple, once the problem was recognized even this was not fully understood for some time. In the particular fuel nozzle design, the water was injected in an axial direction into the airstream and carried through the nozzle nut by entrainment to emerge in streaks of very large, high velocity droplets intermingling with the fuel spray in the combustion zone. Characteristically, the water emerged from the nozzle in clusters around the 360.degree. periphery of the nozzle outlet which corresponded to the nozzle nut holes which admitted the entrained water.
The solution to this problem was adding an annulus formed in the inner diameter of the nut of the fuel nozzle adjacent the juncture point where the water was injected into the fuel spray in the combustion zone of the combustor. This served to distribute the water uniformly around the 360.degree. circumference of the fuel nozzle discharge point and to break up the large water droplets. From actual tests, this produced a significant reduction in smoke emission making an unacceptable engine from this standpoint acceptable.